Product Size:3/4/6 packYou are free to choose. The BLACK+DECKER string trimmer Auto Feed System (AFS) Replacement Spool eases the tedious work of hand winding spools. Designed for use with Black Decker auto feed string trimmers, the 30 foot factory wound replacement spool features a .065 inch diameter line utilizes centrifugal force to automatically feed the cutting string while eliminating bumps and hitches. Compatible with: CST1000, CST1200, CST2000, GH400, GH500, GH600, GH610, GH900 and more. 1.This coil is the perfect substitute BLACK+DECKER replacement spool system eliminates time spent hand winding string trimmers 2.Compatible with most BLACK+DECKER string trimmers; 30 feet replacement line is factory wound for a superior feed 3.This spool utilizes centrifugal force to feed the trimmer line as it is neededSame function as the original spool of BLACK+DECKER, you do nt have to worry about any problems 4.Optimized for extremely high performance and load.